An air bag unit is installed on a fixed portion of car body in front of seat in a vehicle. In an emergency such as vehicle collision, the air bag is inflated instantaneously by the pressure of reaction gas released from an inflator, which is fixed on a fixed portion of car body such as steering wheel or lower portion of instrument panel. Thus, the air bag plays an important role for protecting the occupant from injury caused by collision against car body.
As shown in FIG. 7, such air bag unit 01 comprises an inflator 02, which releases gas as gas generating agent is exploded by collision signal from collision detecting sensor when the deceleration of the vehicle exceeds a certain level, and an air bag 03, which is fixed with respect to the inflator 02 at its base and is inflated by the gas blown out from the inflator 02. With the air bag 03 folded up and placed in a pad, the air bag unit 01 is mounted on a fixed portion of the car body such as central portion of a steering wheel 04 or lower portion of instrument panel 05.
Then, as shown in FIG. 7, the gas generating agent in the inflator 02 reacts when the vehicle is collided, and the air bag 03 is instantaneously inflated and expanded by the generated gas. As the result, the air bag 03 receives the occupant M, who is pushed forward by inertia and protects the occupant M from the collision against car body.
Of such air bag 03 in an air bag unit 01, the air bag 03 for an occupant other than the driver is formed as shown in FIG. 8 (A) as follows: From a piece of base cloth, bag main unit 03a and a pair of lateral segments 03b and 03c, against which the occupant strikes, are cut into the predetermined shapes, and these are sewn up with lugs as shown in FIG. 8 (B).
However, when a plurality of the components (03a, 03b and 03c) of the air bag 03 are cut from a piece of base cloth and are sewn, many steps of processes are required.
Moreover, because it is difficult to mechanize the sewing of base cloth and the sewing of edges, all these works must be done manually, and the works need much labor because there are many points to sew up.
For this reason, the productivity of air bag has been not very high in the past.
To solve the above problems, the object of the present invention is to offer an air bag in an air bag unit, by which it is possible to reduce the number of manufacturing steps and to increase the productivity through mechanization.